<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box{
            width: 200px;
            height: 200px;
            border: red 1px solid;
        }
        .active{
            background-color: red;
        }
    </style>
</head>
<body>
    <div class="box">
        <button>按钮</button>
    </div>
    <div class="box">
        <button>按钮</button>
    </div>
    <div class="box">
        <button>按钮</button>
    </div>
    <script src="jquery.js">
    </script>
    <script>
        //find找子级
        //parent找父级
        $("button").click(function(){
            $(this).parent(".box").css("background-color","red")
        })
    </script>
</body>
</html>